Electronic component

ABSTRACT

An electronic component includes a multilayer body constituted by insulator layers that are laminated in a laminating direction, a primary coil including one or more primary coil conductor layers, a secondary coil including one or more secondary coil conductor layers, and a tertiary coil including one or more tertiary coil conductor layers. The primary coil conductor layers, the secondary coil conductor layers, and the tertiary coil conductor layers are arrayed in the laminating direction. The primary coil, the secondary coil, and tertiary coil constitute a common mode filter, and intervals between two among the one or more primary coil conductor layers, the one or more secondary coil conductor layers, and the one or more tertiary coil conductor layers, every two of those being adjacent to each other in the laminating direction, are not even.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit of priority to Japanese PatentApplication 2015-216265 filed Nov. 4, 2015, the entire content of whichis incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to an electronic component including acommon mode filter.

BACKGROUND

A common mode choke coil disclosed in Japanese Patent No. 4209851, forexample, is known as one disclosure regarding related-art common modefilters. FIG. 12 is a sectional structural view of a common mode chokecoil 510 disclosed in Japanese Patent No. 4209851.

The common mode choke coil 510 comprises a multilayer body 512 and coils514, 516 and 518. In a plan view, the coils 514, 516 and 518 extend fromthe outer peripheral side toward the inner peripheral side in asubstantially spiral shape while circling clockwise, and they areoverlapped with one another. The coil 518 is sandwiched between thecoils 514 and 516 from the upper and lower sides. In the common modechoke coil 510, a high frequency signal is transferred to each of thecoils 514 and 516, and a ground potential is connected to the coil 518.

SUMMARY

The inventors of this application have conducted studies on the commonmode choke coil 510 disclosed in Japanese Patent No. 4209851 for atechnique of transferring a high frequency signal to each of the coils514, 516 and 518, and removing common mode noise from the differentialsignal between two high frequency signals among those three highfrequency signals. In that case, the common mode choke coil 510 ismounted to a circuit board described below. FIG. 13 is a plan view of acircuit board 600 to which the common mode choke coil 510 is to bemounted. FIG. 14 is a sectional structural view, taken along 14-14, ofthe circuit board 600 to which the common mode choke coil 510 is to bemounted.

The circuit board 600 includes a board body 602, signal lines 604, 606and 608, and a ground conductor layer 610. The board body 602 is aninsulating substrate in the form of a plate, and it has an upper surfaceand a bottom surface. The signal lines 604, 606 and 608 aresubstantially linear conductive layers that are disposed on the uppersurface of the board body 602, and that extend parallel to one another.The ground conductor layer 610 is disposed on the bottom surface of theboard body 602 in an overlapping relation to the signal lines 604, 606and 608. Thus, the signal lines 604, 606 and 608 and the groundconductor layer 610 constitute a microstrip line structure.

When the common mode choke coil 510 is mounted to the above-describedcircuit board 600, the signal line 604 is connected to the coil 514, thesignal line 606 is connected to the coil 518, and the signal line 608 isconnected to the coil 516.

In the common mode choke coil 510 and the circuit board 600 disclosed inJapanese Patent No. 4209851, however, it is difficult to hold matchingbetween a differential impedance between the coil 514 and the coil 516and a differential impedance between the signal line 604 and the signalline 608.

In the common mode choke coil 510, a difference occurs in differentialimpedances between two coils among the coils 514, 516 and 518 asdescribed below. As illustrated in FIG. 12, the coil 514 and the coil518 are adjacently opposed to each other, and the coil 516 and the coil518 are adjacently opposed to each other. On the other hand, because thecoil 518 is present between the coil 514 and the coil 516, the coil 514and the coil 516 are not adjacently opposed to each other and are spacedthrough a relatively large distance. Accordingly, a capacitancegenerated between the coil 514 and the coil 516 is smaller than thatgenerated between the coil 514 and the coil 518 and that generatedbetween the coil 516 and the coil 518. As a result, the differentialimpedance generated between the coil 514 and the coil 516 is larger thanthat generated between the coil 514 and the coil 518 and that generatedbetween the coil 516 and the coil 518.

In the circuit board 600, a difference occurs in differential impedancesbetween two signal lines among the signal lines 604, 606 and 608 asdescribed below. As illustrated in FIG. 13, the signal line 604 and thesignal line 606 are adjacent to each other, and the signal line 606 andthe signal line 608 are adjacent to each other. On the other hand,because the signal line 606 is present between the signal line 604 andthe signal line 608, the signal line 604 and the signal line 608 are notadjacent to each other and are spaced through a relatively largedistance. Accordingly, a capacitance generated between the signal line604 and the signal line 608 is smaller than that generated between thesignal line 604 and the signal line 606 and that generated between thesignal line 606 and the signal line 608. As a result, the differentialimpedance generated between the signal line 604 and the signal line 608is larger than that generated between the signal line 604 and the signalline 606 and that generated between the signal line 606 and the signalline 608.

The following description is made, for example, in connection with anexample in which the differential impedance between the coil 514 and thecoil 518 and the differential impedance between the coil 516 and thecoil 518 are matched respectively with the differential impedancebetween the signal line 604 and the signal line 606 and the differentialimpedance between the signal line 606 and the signal line 608. In thatcase, the differential impedance between the coil 514 and the coil 516is larger than that between the signal line 604 and the signal line 608.Accordingly, an adjustment of the differential impedance is required toreduce reflection between the common mode choke coil 510 and the circuitboard 600.

On the other hand, because the signal lines 604, 606 and 608 are opposedto each other at their lateral surfaces between two adjacent lateralsurfaces an area in which the adjacent signal lines are opposed to eachother is small and a small capacitance is generated between the adjacentsignal lines. Accordingly, an adjustable range of the differentialimpedances between two signal lines among the signal lines 604, 606 and608 to be adjusted is relatively small, and the adjustment in thecircuit board 600 is comparatively difficult.

Furthermore, in the circuit board 600, the signal lines 604, 606 and 608are two-dimensionally arranged in the same layer. One conceivablesolution for relatively increasing the adjustable range of thedifferential impedances between two signal lines among the signal lines604, 606 and 608 is to three-dimensionally arrange the signal lines 604,606 and 608 in different layers. However, such a solution is impracticalbecause of an increased manufacturing cost of the circuit board 600.Thus, the adjustment in the common mode choke coil 510, the adjustmentof the differential impedance between the coils 514 and 516 for example,is demanded.

Accordingly, an object of the present disclosure is, in an electroniccomponent including a common mode filter constituted by three coils, toadjust differential impedances between two coils among the coils.

An electronic component according to one embodiment of the presentdisclosure comprises a multilayer body constituted by insulator layersthat are laminated in a laminating direction, a primary coil includingone or more primary coil conductor layers each disposed on one of theinsulator layers, a secondary coil including one or more secondary coilconductor layers each disposed on one of the insulator layers, and atertiary coil including one or more tertiary coil conductor layers eachdisposed on one of the insulator layers, wherein the primary coilconductor layers, the secondary coil conductor layers, and the tertiarycoil conductor layers are arrayed in the laminating direction, theprimary coil, the secondary coil and tertiary coil constitute a commonmode filter, and intervals between two among the one or more primarycoil conductor layers, the one or more secondary coil conductor layers,and the one or more tertiary coil conductor layers, every two of thosetwo being adjacent to each other in the laminating direction, are noteven.

With the one embodiment of the present disclosure, in the electroniccomponent including the common mode filter constituted by three coils,differential impedances between two coils among the three coils can beadjusted.

Other features, elements, characteristics and advantages of the presentdisclosure will become more apparent from the following detaileddescription of some embodiments of the present disclosure with referenceto the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an external perspective view of each of electronic componentsaccording to an embodiment of the present disclosure and according tofirst to fourth modifications.

FIG. 2 is an exploded perspective view of the electronic component,illustrated in FIG. 1, according to the embodiment.

FIG. 3 is a sectional structural view, taken along 3-3, of theelectronic component, illustrated in FIG. 1, according to theembodiment.

FIG. 4 is a graph representing a simulation result of a first model.

FIG. 5 is a graph representing a simulation result of a second model.

FIG. 6A is a graph representing a simulation result of the first model.

FIG. 6B is a graph representing a simulation result of the second model.

FIG. 7A is a schematic view illustrating a positional relation amongcoil conductor layers and a parallel coil conductor layer of theelectronic component according to the embodiment.

FIG. 7B is a schematic view illustrating a positional relationship amongcoil conductor layers and a parallel coil conductor layer of theelectronic component according to the first modification.

FIG. 8A is an exploded perspective view of a multilayer body of theelectronic component according to the first modification.

FIG. 8B is a sectional structural view, taken along 3-3, of theelectronic component, illustrated in FIG. 1, according to the firstmodification.

FIG. 9 is a schematic view illustrating a positional relationship amongcoil conductor layers and a parallel coil conductor layer of theelectronic component according to the second modification.

FIG. 10 is a sectional structural view, taken along 3-3, of theelectronic component, illustrated in FIG. 1, according to the thirdmodification.

FIG. 11 is a sectional structural view, taken along 3-3, of theelectronic component, illustrated in FIG. 1, according to the fourthmodification.

FIG. 12 is a sectional structural view of a common mode choke coildisclosed in Japanese Patent No. 4209851.

FIG. 13 is a plan view of a circuit board to which the common mode chokecoil is mounted.

FIG. 14 is a sectional structural view, taken along 14-14 in FIG. 13, ofthe circuit board to which the common mode choke coil is mounted.

DETAILED DESCRIPTION

Electronic components according to some embodiments of the presentdisclosure will be described below.

(Configuration of Electronic Component)

First, a configuration of an electronic component 10 according to oneembodiment of the present disclosure is described with reference to thedrawings. FIG. 1 is an external perspective view of each of electroniccomponents 10 and 10 a to 10 d. FIG. 2 is an exploded perspective viewof the electronic component 10 illustrated in FIG. 1. FIG. 3 is asectional structural view, taken along 3-3, of the electronic component10 illustrated in FIG. 1. In the following description, an up-downdirection is a laminating direction of the electronic component 10, afront-back direction is a direction in which a long side of theelectronic component 10 extends in a plan view, and a left-rightdirection is a direction in which a short side of the electroniccomponent 10 extends in the plan view. The up-down direction, thefront-back direction, and the left-right direction are orthogonal to oneanother. The laminating direction represents a direction in whichlater-described insulator layers are laminated, a direction orthogonalto a principal surface of insulator layers on which insulator layers arelaminated to be more specific. The plan view is one viewed from thelaminating direction, for example, a view when viewed from above. Alower side and an upper side is one example of one side and other sidein the laminating direction.

As illustrated in FIGS. 1 to 3, the electronic component 10 includes amain body 12, outer electrodes 14 a to 14 f, connecting portions 16 a to16 f, lead-out portions 50 to 57, a primary coil L1, a secondary coilL2, and a tertiary coil L3.

As illustrated in FIGS. 1 and 2, the main body 12 has a substantiallyrectangular parallelepiped shape, and includes magnetic substrates 20 aand 20 b, a multilayer body 22, and a magnetic layer 24. The magneticsubstrate 20 a, the magnetic layer 24, the multilayer body 22, and themagnetic substrate 20 b are successively laminated in the mentionedorder from the lower side toward the upper side.

The magnetic substrates 20 a and 20 b are each a plate-like memberhaving a substantially rectangular shape in the plan view. In thefollowing, a principal surface of each of the magnetic substrates 20 aand 20 b on the upper side is called an upper surface, and a principalsurface of each of the magnetic substrates 20 a and 20 b on the lowerside is called a bottom surface. The magnetic substrate 20 b is partlycut out at four corners and the middle of two long sides thereof in theplan view. More specifically, a cutout having a substantially sectorshape with a central angle of about 90 degrees in the plan view isformed at each of the four corners of the magnetic substrate 20 b. Acutout having a substantially semicircular shape in the plan view isformed at the middle of each of the two long sides of the magneticsubstrate 20 b. Those six cutouts extend along lateral surfaces of themagnetic substrate 20 b in the up-down direction from the upper surfaceof the magnetic substrate 20 b until reaching the bottom surfacethereof.

The magnetic substrates 20 a and 20 b are each fabricated by cutting asintered ferrite ceramic. Alternatively, the magnetic substrates 20 aand 20 b may be each fabricated by coating a paste, which is made ofcalcined ferrite powder and a binder, over a ceramic substrate made of,e.g., alumina, or by laminating green sheets each made of a ferritematerial, and firing the laminated green sheets.

The outer electrodes 14 a to 14 f are disposed on the bottom surface ofthe magnetic substrate 20 b, and each outer electrode has asubstantially rectangular shape. More specifically, the outer electrode14 a is disposed at a rear left corner of the bottom surface of themagnetic substrate 20 b. The outer electrode 14 b is disposed at themiddle of a long side of the bottom surface of the magnetic substrate 20b on the left side. The outer electrode 14 c is disposed at a front leftcorner of the bottom surface of the magnetic substrate 20 b. Thus, theouter electrodes 14 a, 14 b and 14 c are arrayed to position in thementioned order from the rear side toward the front side. The outerelectrode 14 d (one example of a first outer electrode) is disposed at arear right corner of the bottom surface of the magnetic substrate 20 b.The outer electrode 14 e (one example of a second outer electrode) isdisposed at the middle of a long side of the bottom surface of themagnetic substrate 20 b on the right side. The outer electrode 14 f (oneexample of a third outer electrode) is disposed at a front right cornerof the bottom surface of the magnetic substrate 20 b. Thus, the outerelectrodes 14 d, 14 e and 14 f are arrayed to position in the mentionedorder in a direction (one example of a predetermined direction) towardthe front side from the rear side. The outer electrodes 14 a to 14 f areeach fabricated by forming an Au film, a Ni film, a Cu film, and a Tifilm in a laminated state with sputtering. Alternatively, the outerelectrodes 14 a to 14 f may be each fabricated by applying and firing apaste that contains a metal such as Ag or Cu, or by forming a film of,e.g., Ag or Cu with evaporation or plating.

The connecting portions 16 a to 16 f are disposed respectively in thesix cutouts formed in the magnetic substrate 20 b. The connectingportion 16 a is disposed in the cutout positioned at a rear left cornerof the magnetic substrate 20 b and is connected at its lower end to theouter electrode 14 a. The connecting portion 16 b is disposed in thecutout positioned at the middle of a long side of the magnetic substrate20 b on the left side and is connected at its lower end to the outerelectrode 14 b. The connecting portion 16 c is disposed in the cutoutpositioned at a front left corner of the magnetic substrate 20 b and isconnected at its lower end to the outer electrode 14 c. The connectingportion 16 d is disposed in the cutout positioned at a rear right cornerof the magnetic substrate 20 b and is connected at its lower end to theouter electrode 14 d. The connecting portion 16 e is disposed in thecutout positioned at the middle of a long side of the magnetic substrate20 b on the right side and is connected at its lower end to the outerelectrode 14 e. The connecting portion 16 f is disposed in the cutoutpositioned at a front right corner of the magnetic substrate 20 b and isconnected at its lower end to the outer electrode 14 f. The connectingportions 16 a to 16 f are each fabricated by forming a conductor film,which contains Cu as a main ingredient, with plating. Alternatively, theconnecting portions 16 a to 16 f may be each fabricated using a materialwith high electrical conductivity, such as Ag or Au.

The multilayer body 22 includes insulator layers 26 a to 26 f (oneexample of a plurality of insulator layers) that are laminated on theupper surface of the magnetic substrate 20 b, and it has a substantiallyrectangular shape in the plan view. The insulator layers 26 a to 26 fare laminated to array in the mentioned order from the upper side towardthe lower side, and they have substantially the same size as the uppersurface of the magnetic substrate 20 b. Four corners and the middle oftwo long sides of each of the insulator layers 26 b to 26 f are cut outin the plan view.

The insulator layers 26 a to 26 f are each made of polyimide.Alternatively, the insulator layers 26 a to 26 f may be each made of aninsulating resin such as benzocyclobutene, or made of an insulatinginorganic material such as glass-ceramic. In the following, a principalsurface of each of the insulator layers 26 a to 26 f on the upper sideis called an upper surface, and a principal surface of each of theinsulator layers 26 a to 26 f on the lower side is called a bottomsurface.

The magnetic layer 24 is disposed between the multilayer body 22 and themagnetic substrate 20 a, and it serves to not only planarize an uppersurface of the multilayer body 22, but also join the multilayer body 22and the magnetic substrate 20 a to each other. The magnetic layer 24 ismade of, e.g., a mixture of powder of a magnetic material and resin.

The primary coil L1 is disposed inside the multilayer body 22 andincludes a coil conductor layer 30 a, one example of a primary coilconductor layer. The coil conductor layer 30 a is disposed on the uppersurface of the insulator layer 26 f, and it has a substantially spiralshape extending from the outer peripheral side toward the innerperipheral side while circling clockwise in the plan view. In thisembodiment, the coil conductor layer 30 a has a length corresponding toabout four times the circumference of the spiral shape. The center ofthe coil conductor layer 30 a is substantially aligned with the center(crossed point of diagonal lines) of the electronic component 10 in theplan view.

The lead-out portion 50 connects one end of the primary coil L1 (i.e.,an end portion of the coil conductor layer 30 a on the outer peripheralside) to the outer electrode 14 a, and it does not have thesubstantially spiral shape in the plan view, as illustrated in FIG. 2.The lead-out portion 50 includes a lead-out conductor layer 40 a and aconnecting conductor 70 a. The connecting conductor 70 a is a conductorhaving a substantially triangular prism shape and disposed at the rearleft corners of the insulator layers 26 b to 26 f. In FIG. 2, for thesake of easier understanding, the connecting conductor 70 a isillustrated in a state divided into five pieces. Similarly to theconnecting conductor 70 a, later-described connecting conductors 70 b to70 f are also each illustrated in a state divided into five pieces. Theconnecting conductor 70 a extends in the up-down direction from theupper surface of the insulator layer 26 b to the bottom surface of theinsulator layer 26 f, and is connected at its lower end to theconnecting portion 16 a.

The lead-out conductor layer 40 a is disposed on the upper surface ofthe insulator layer 26 f, and is connected to the outer end portion ofthe coil conductor layer 30 a and further to the connecting conductor 70a. The lead-out conductor layer 40 a does not have the substantiallyspiral shape in the plan view, and it extends leftward from the outerend portion of the coil conductor layer 30 a. As illustrated in anenlarged view in FIG. 2, a boundary between the coil conductor layer 30a and the lead-out conductor layer 40 a is at a position where thelead-out conductor layer 40 a departs from the locus of thesubstantially spiral shape formed by the coil conductor layer 30 a. Withsuch an arrangement, the one end of the primary coil L1 (i.e., the outerend portion of the coil conductor layer 30 a) and the outer electrode 14a are connected to each other through the lead-out portion 50 (includingthe lead-out conductor layer 40 a and the connecting conductor 70 a) andthe connecting portion 16 a.

The lead-out portion 53 connects the other end of the primary coil L1(i.e., an inner end portion of the coil conductor layer 30 a) to theouter electrode 14 d, and it does not have the substantially spiralshape in the plan view, as illustrated in FIG. 2. The lead-out portion53 includes an interlayer connecting conductor v1, a lead-out conductorlayer 60, and a connecting conductor 70 d. The connecting conductor 70 dis a conductor having a substantially triangular prism shape anddisposed at the rear right corners of the insulator layers 26 b to 26 f.The connecting conductor 70 d extends in the up-down direction from theupper surface of the insulator layer 26 b to the bottom surface of theinsulator layer 26 f, and is connected at its lower end to theconnecting portion 16 d.

The interlayer connecting conductor v1 is a conductor penetratingthrough the insulator layers 26 b to 26 f in the up-down direction, andit has a substantially linear shape extending in the left-rightdirection in the plan view. The interlayer connecting conductor v1 isdisposed in rear half regions of the insulator layers 26 b to 26 f inthe plan view, and is connected to the end portion of the coil conductorlayer 30 a on the inner peripheral side.

The lead-out conductor layer 60, one example of a first lead-outconductor layer, is disposed on the upper surface of the insulator layer26 c, and it does not have the substantially spiral shape in the planview. The lead-out conductor layer 60 relays connection between theinner end portion of the coil conductor layer 30 a, one example of anend primary coil conductor layer, and the outer electrode 14 d. Morespecifically, the lead-out conductor layer 60 is connected to theinterlayer connecting conductor v1 and further to the connectingconductor 70 d. With such an arrangement, the other end of the primarycoil L1 (i.e., the inner end portion of the coil conductor layer 30 a)and the outer electrode 14 d are connected to each other through thelead-out portion 53 (including the interlayer connecting conductor v1,the lead-out conductor layer 60, and the connecting conductor 70 d) andthe connecting portion 16 d.

The secondary coil L2 is disposed inside the multilayer body 22 andincludes the coil conductor layer 32 a, one example of a secondary coilconductor layer. The coil conductor layer 32 a is disposed on the uppersurface of the insulator layer 26 e, and it has a substantially spiralshape extending from the outer peripheral side toward the innerperipheral side while circling clockwise in the plan view. In thisembodiment, the coil conductor layer 32 a has a length corresponding toabout four times the circumference of the spiral shape. The center ofthe coil conductor layer 32 a is substantially aligned with the center(crossed point of the diagonal lines) of the electronic component 10 inthe plan view.

As illustrated in FIGS. 2 and 3, the coil conductor layer 32 a overlapsthe coil conductor layer 30 a substantially over the entire length inthe plan view. Therefore, a region surrounded by the coil conductorlayer 30 a (i.e., an inner magnetic path of the primary coil L1) and aregion surrounded by the coil conductor layer 32 a (i.e., an innermagnetic path of the secondary coil L2) overlap with each other in theplan view. Thus, the coil conductor layer 30 a (i.e., the primary coilL1) and the coil conductor layer 32 a (i.e., the secondary coil L2) aremagnetically coupled to each other. However, positions of both ends ofthe coil conductor layer 30 a and positions of both ends of the coilconductor layer 32 a are set to be different such that the lead-outportions 50 and 53 and the later-described lead-out portions 51 and 54do not interfere with each other. More specifically, the end portion ofthe coil conductor layer 32 a on the outer peripheral side is positionedupstream of the end portion of the coil conductor layer 30 a on theouter peripheral side in the clockwise direction. The end portion of thecoil conductor layer 32 a on the inner peripheral side is positionedupstream of the end portion of the coil conductor layer 30 a on theinner peripheral side in the clockwise direction. With such anarrangement, the length of the coil conductor layer 30 a and the lengthof the coil conductor layer 32 a are substantially equal to each other.Since the coil conductor layer 30 a and the coil conductor layer 32 aare just required to be magnetically coupled, they are not alwaysrequired to overlap with each other over the entire length, and they maybe slightly deviated in the front-back direction or the left-rightdirection. In other words, it is just required that the coil conductorlayer 32 a is disposed on the upper side of the coil conductor layer 30a.

The lead-out portion 51 connects one end of the secondary coil L2 (i.e.,an outer end portion of the coil conductor layer 32 a) to the outerelectrode 14 b, and it does not have the substantially spiral shape inthe plan view, as illustrated in FIG. 2. The lead-out portion 51includes a lead-out conductor layer 42 a and a connecting conductor 70b. The connecting conductor 70 b is a conductor having a substantiallyquadrangular prism shape and disposed at the middle of the long sides ofthe insulator layers 26 b to 26 f on the left side. The connectingconductor 70 b extends in the up-down direction from the upper surfaceof the insulator layer 26 b to the bottom surface of the insulator layer26 f, and is connected at its lower end to the connecting portion 16 b.

The lead-out conductor layer 42 a is disposed on the upper surface ofthe insulator layer 26 e, and is connected to the outer end portion ofthe coil conductor layer 32 a and further to the connecting conductor 70b. The lead-out conductor layer 42 a does not have the substantiallyspiral shape in the plan view, and it extends leftward from the outerend portion of the coil conductor layer 32 a. With such an arrangement,the one end of the secondary coil L2 (i.e., the outer end portion of thecoil conductor layer 32 a) and the outer electrode 14 b are connected toeach other through the lead-out portion 51 (including the lead-outconductor layer 42 a and the connecting conductor 70 b) and theconnecting portion 16 b.

The lead-out portion 54 connects the other end of the secondary coil L2(i.e., an inner end portion of the coil conductor layer 32 a) to theouter electrode 14 e, and it does not have the substantially spiralshape in the plan view, as illustrated in FIG. 2. The lead-out portion54 includes an interlayer connecting conductor v2, a lead-out conductorlayer 62, and a connecting conductor 70 e. The connecting conductor 70 eis a conductor having a substantially quadrangular prism shape anddisposed at the middle of the long sides of the insulator layers 26 b to26 f on the right side. The connecting conductor 70 e extends in theup-down direction from the upper surface of the insulator layer 26 b tothe bottom surface of the insulator layer 26 f, and is connected at itslower end to the connecting portion 16 e.

The interlayer connecting conductor v2 is a conductor penetratingthrough the insulator layers 26 b to 26 e in the up-down direction, andit has a substantially linear shape extending in the left-rightdirection in the plan view. The interlayer connecting conductor v2 isdisposed in central regions of the insulator layers 26 b to 26 e in theplan view, and is connected to the end portion of the coil conductorlayer 32 a on the inner peripheral side.

The lead-out conductor layer 62, one example of a second lead-outconductor layer, is disposed on the upper surface of the insulator layer26 c, and it does not have the substantially spiral shape in the planview. The lead-out conductor layer 62 relays connection between theinner end portion of the coil conductor layer 32 a, one example of anend secondary coil conductor layer, and the outer electrode 14 e. Morespecifically, the lead-out conductor layer 62 is connected to theinterlayer connecting conductor v2 and further to the connectingconductor 70 e. With such an arrangement, the other end of the secondarycoil L2 (i.e., the inner end portion of the coil conductor layer 32 a)and the outer electrode 14 e are connected to each other through thelead-out portion 54 (including the interlayer connecting conductor v2,the lead-out conductor layer 62, and the connecting conductor 70 e) andthe connecting portion 16 e.

The tertiary coil L3 is disposed inside the multilayer body 22 andincludes the coil conductor layer 34 a, one example of a tertiary coilconductor layer. The coil conductor layer 34 a is disposed on the uppersurface of the insulator layer 26 d, and it has a substantially spiralshape extending from the outer peripheral side toward the innerperipheral side while circling clockwise in the plan view. In thisembodiment, the coil conductor layer 34 a has a length corresponding toabout four times the circumference of the spiral shape. The center ofthe coil conductor layer 34 a is substantially aligned with the center(crossed point of the diagonal lines) of the electronic component 10 inthe plan view.

As illustrated in FIGS. 2 and 3, the coil conductor layer 34 a overlapsthe coil conductor layers 30 a and 32 a substantially over the entirelength in the plan view. Therefore, the region surrounded by the coilconductor layer 30 a (i.e., the inner magnetic path of the primary coilL1), the region surrounded by the coil conductor layer 32 a (i.e., theinner magnetic path of the secondary coil L2), and a region surroundedby the coil conductor layer 34 a (i.e., an inner magnetic path of thetertiary coil L3) overlap with one another in the plan view. Thus, thecoil conductor layer 30 a (i.e., the primary coil L1), the coilconductor layer 32 a (i.e., the secondary coil L2), and the coilconductor layer 34 a (i.e., the tertiary coil L3) are magneticallycoupled to one another. However, the positions of both the ends of thecoil conductor layer 30 a, the positions of both the ends of the coilconductor layer 32 a, and positions of both ends of the coil conductorlayer 34 a are set to be different such that the lead-out portions 50and 53, the lead-out portions 51 and 54, and later-described lead-outportions 52 and 55 do not interfere with one another. More specifically,the end portion of the coil conductor layer 34 a on the outer peripheralside is positioned upstream of the end portions of the coil conductorlayers 30 a and 32 a on the outer peripheral side in the clockwisedirection. The end portion of the coil conductor layer 34 a on the innerperipheral side is positioned upstream of the end portions of the coilconductor layers 30 a and 32 a on the inner peripheral side in theclockwise direction. With such an arrangement, the length of the coilconductor layer 30 a, the length of the coil conductor layer 32 a, andthe length of the coil conductor layer 34 a are substantially equal toone another. Since the coil conductor layer 30 a, the coil conductorlayer 32 a, and the coil conductor layer 34 a are just required to bemagnetically coupled, they are not always required to overlap with oneanother over the entire length, and they may be slightly deviated in thefront-back direction or the left-right direction. In other words, it isjust required that the coil conductor layer 34 a is disposed on theupper side of the coil conductor layers 30 a and 32 a.

The lead-out portion 52 connects one end of the tertiary coil L3 (i.e.,an outer end portion of the coil conductor layer 34 a) to the outerelectrode 14 c, and it does not have the substantially spiral shape inthe plan view, as illustrated in FIG. 2. The lead-out portion 52includes a lead-out conductor layer 44 a and a connecting conductor 70c. The connecting conductor 70 c is a conductor having a substantiallytriangular prism shape and disposed at the front left corners of theinsulator layers 26 b to 26 f. The connecting conductor 70 c extends inthe up-down direction from the upper surface of the insulator layer 26 bto the bottom surface of the insulator layer 26 f, and is connected atits lower end to the connecting portion 16 c.

The lead-out conductor layer 44 a is disposed on the upper surface ofthe insulator layer 26 d, and is connected to the outer end portion ofthe coil conductor layer 34 a and further to the connecting conductor 70c. The lead-out conductor layer 44 a does not have the substantiallyspiral shape in the plan view, and it extends forward from the outer endportion of the coil conductor layer 34 a. With such an arrangement, theone end of the tertiary coil L3 (i.e., the outer end portion of the coilconductor layer 34 a) and the outer electrode 14 c are connected to eachother through the lead-out portion 52 (including the lead-out conductorlayer 44 a and the connecting conductor 70 c) and the connecting portion16 c.

The lead-out portion 55 connects the other end of the tertiary coil L3(i.e., an inner end portion of the coil conductor layer 34 a) to theouter electrode 14 f, and it does not have the substantially spiralshape in the plan view, as illustrated in FIG. 2. The lead-out portion55 includes an interlayer connecting conductor v3, a lead-out conductorlayer 64, and a connecting conductor 70 f. The connecting conductor 70 fis a conductor having a substantially triangular prism shape anddisposed at the front right corners of the insulator layers 26 b to 26f. The connecting conductor 70 f extends in the up-down direction fromthe upper surface of the insulator layer 26 b to the bottom surface ofthe insulator layer 26 f, and is connected at its lower end to theconnecting portion 16 f.

The interlayer connecting conductor v3 is a conductor penetratingthrough the insulator layers 26 b to 26 d in the up-down direction, andit has a substantially linear shape extending in the left-rightdirection in the plan view. The interlayer connecting conductor v3 isdisposed in front half regions of the insulator layers 26 b to 26 d inthe plan view, and is connected to the end portion of the coil conductorlayer 34 a on the inner peripheral side.

The lead-out conductor layer 64, one example of a third lead-outconductor layer, is disposed on the upper surface of the insulator layer26 c, and it does not have the substantially spiral shape in the planview. The lead-out conductor layer 64 relays connection between theinner end portion of the coil conductor layer 34 a, one example of anend tertiary coil conductor layer, and the outer electrode 14 f. Morespecifically, the lead-out conductor layer 64 is connected to theinterlayer connecting conductor v3 and further to the connectingconductor 70 f. With such an arrangement, the other end of the tertiarycoil L3 (i.e., the inner end portion of the coil conductor layer 34 a)and the outer electrode 14 f are connected to each other through thelead-out portion 55 (including the interlayer connecting conductor v3,the lead-out conductor layer 64, and the connecting conductor 70 f) andthe connecting portion 16 f.

The primary coil L1 further includes a parallel coil conductor layer 36,one example of a parallel primary coil conductor layer. The parallelcoil conductor layer 36 has the same shape as the coil conductor layer30 a, one example of a predetermined primary coil conductor layer. Theparallel coil conductor layer 36 is electrically connected to the coilconductor layer 30 a in parallel, and is disposed on the upper side ofthe coil conductor layer 34 a, one example of a predetermined tertiarycoil conductor layer, which is the coil conductor layer disposed at anuppermost position among the coil conductor layers 30 a, 32 a and 34 a.In other words, the parallel coil conductor layer 36 is disposed on theupper surface of the insulator layer 26 b, and is positioned above thecoil conductor layer 34 a and the lead-out conductor layers 60, 62 and64. Furthermore, the parallel coil conductor layer 36 has asubstantially spiral shape extending from the outer peripheral sidetoward the inner peripheral side while circling clockwise in the planview as the coil conductor layer 30 a. In this embodiment, the parallelcoil conductor layer 36 has a length corresponding to about four timesthe circumference of the spiral shape. The center of the parallel coilconductor layer 36 is substantially aligned with the center (crossedpoint of the diagonal lines) of the electronic component 10 in the planview.

The lead-out portion 56 connects an outer end portion of the parallelcoil conductor layer 36 to the outer electrode 14 a, and it does nothave the substantially spiral shape in the plan view, as illustrated inFIG. 2. The lead-out portion 56 includes a lead-out conductor layer 46and the connecting conductor 70 a. The lead-out conductor layer 46 isdisposed on the upper surface of the insulator layer 26 b, and isconnected to the outer end portion of the parallel coil conductor layer36 and further to the connecting conductor 70 a. The lead-out conductorlayer 46 does not have the substantially spiral shape in the plan view,and it extends leftward from the outer end portion of the parallel coilconductor layer 36. With such an arrangement, the outer end portion ofthe parallel coil conductor layer 36 and the outer electrode 14 a areconnected to each other through the lead-out portion 56 (including thelead-out conductor layer 46 and the connecting conductor 70 a) and theconnecting portion 16 a.

The lead-out portion 57 connects the inner end portion of the parallelcoil conductor layer 36 to the outer electrode 14 d, and it does nothave the substantially spiral shape in the plan view, as illustrated inFIG. 2. The lead-out portion 57 includes the interlayer connectingconductor v1, the lead-out conductor layer 60, and the connectingconductor 70 d. Because the interlayer connecting conductor v1, thelead-out conductor layer 60, and the connecting conductor 70 d havealready been described above, further description of those members isomitted here. With the above-mentioned arrangement, the inner endportion of the parallel coil conductor layer 36 and the outer electrode14 d are connected to each other through the lead-out portion 57(including the interlayer connecting conductor v1, the lead-outconductor layer 60, and the connecting conductor 70 d) and theconnecting portion 16 d. Thus, the parallel coil conductor layer 36 iselectrically connected to the coil conductor layer 30 a in parallel.

The coil conductor layers 30 a, 32 a and 34 a, the parallel coilconductor layer 36, the lead-out conductor layer 40 a, 42 a, 44 a, 46,60, 62 and 64, and the connecting conductors 70 a to 70 f are eachformed by coating a film with sputtering of Ag. Alternatively, the coilconductor layers 30 a, 32 a and 34 a, the parallel coil conductor layer36, the lead-out conductor layer 40 a, 42 a, 44 a, 46, 60, 62 and 64,and the connecting conductors 70 a to 70 f may be formed using anothermaterial with high electrical conductivity, such as Cu or Au.

As described above, in the primary coil L1, the coil conductor layer 30a and the parallel coil conductor layer 36 have a substantially sameshape, and they are electrically connected in parallel. Moreover, thelength of the coil conductor layer 30 a, the length of the coilconductor layer 32 a, the length of the coil conductor layer 34 a, andthe length of the parallel coil conductor layer 36 are substantiallyequal to one another. Therefore, current paths of the primary coil L1,the secondary coil L2, and the tertiary coil L3 are substantially equalto one another in length. The expression “current paths aresubstantially equal in length” implies that slight differences among thelengths of the coil conductor layers 30 a, 32 a, 34 a and 36 areregarded to be not substantial, those slight differences being generatedby arranging the positions of the lead-out conductor layer 40 a, 42 a,44 a and 46 and the interlayer connecting conductors v1 to v3 so as notto interfere with one another.

Moreover, the coil conductor layers 30 a, 32 a and 34 a and the parallelcoil conductor layer 36 are constituted such that a total of a sectionalarea of the coil conductor layer 30 a and a sectional area of theparallel coil conductor layer 36 is substantially equal to a sectionalarea of the coil conductor layer 32 a and a sectional area of the coilconductor layer 34 a. More specifically, as illustrated in FIG. 3, aline width of the coil conductor layer 30 a, a line width of the coilconductor layer 32 a, a line width of the coil conductor layer 34 a, anda line width of the parallel coil conductor layer 36 are substantiallyequal to one another as denoted by a line width w1. However, each of thecoil conductor layers 32 a and 34 a has a thickness d1, and each of thecoil conductor layer 30 a and the parallel coil conductor layer 36 has athickness d2. The thickness d2 is about half of the thickness d1. Thus,the respective sectional areas of the coil conductor layer 30 a and theparallel coil conductor layer 36 are substantially equal to each otherand are each about half the sectional area of each of the coil conductorlayers 32 a and 34 a. Accordingly, the total of the sectional area ofthe coil conductor layer 30 a and the sectional area of the parallelcoil conductor layer 36 is substantially equal to the sectional area ofthe coil conductor layer 32 a and the sectional area of the coilconductor layer 34 a. On that condition, a resistance value of each ofthe coil conductor layer 30 a and the parallel coil conductor layer 36is about twice that of each of the coil conductor layers 32 a and 34 a.In this respect, the coil conductor layer 30 a and the parallel coilconductor layer 36 are electrically connected in parallel. Thus, in thecurrent paths of the primary coil L1, the secondary coil L2, and thetertiary coil L3, a sectional area of the primary coil L1, a sectionalarea of the secondary coil L2, and a sectional area of the tertiary coilL3 are substantially equal to one another. As a result, the resistancevalue of the primary coil L1, the resistance value of the secondary coilL2, and the resistance value of the tertiary coil L3 are substantiallyequal to one another.

The sectional area of the coil conductor layer in the above descriptionis defined as a sectional area taken in a section of the coil conductorlayer perpendicular to a direction in which the coil conductor layerextends lengthwise. The thickness of the coil conductor layer is definedas a thickness of the coil conductor layer in the up-down direction. Theline width of the coil conductor layer is defined as a width of thesection of the coil conductor layer perpendicular to the extendingdirection of the coil conductor layer, the width being taken in adirection perpendicular to the up-down direction of the coil conductorlayer.

Furthermore, an interval D1 between the two coil conductor layers 30 aand 32 a adjacent to each other in the up-down direction and an intervalD1 between the two coil conductor layers 32 a and 34 a adjacent to eachother in the up-down direction are substantially equal to each other. Inother words, the intervals between two coil conductor layers among thecoil conductor layers 30 a, 32 a and 34 a, every two of those beingadjacent to each other in the up-down direction, are substantially theeven. However, an interval D2 between the coil conductor layers 34 a andthe parallel coil conductor layer 36 is larger than the interval D1between the coil conductor layer 30 a and the coil conductor layer 32 aand the interval D1 between the coil conductor layer 32 a and the coilconductor layer 34 a. The reason resides in that the lead-out conductorlayers 60, 62 and 64 are disposed between the parallel coil conductorlayer 36 and the coil conductor layer 34 a in the up-down direction.Thus, in the electronic component 10, the intervals between two amongthe coil conductor layers 30 a, 32 a and 34 a and the parallel coilconductor layer 36, every two of those being adjacent to each other inthe up-down direction, are not even. Here, the interval between the coilconductor layers is defined as a distance between opposing surfaces ofthe two adjacent coil conductor layers. The expression “the intervalsare not even” is not limited to the case where all the intervals aredifferent, and it implies that at least one of the intervals may bedifferent from the remaining distances. In such a case, the remainingdistances may be all the same.

An operation of the electronic component 10 having the aboveconfiguration will be described below. The outer electrodes 14 a to 14 care used as input terminals for example. The outer electrodes 14 d to 14f are used as output terminals for example. The primary coil L1, thesecondary coil L2, and the tertiary coil L3 are magnetically coupled.

A first signal S1, a second signal S2, and a third signal S3 are inputrespectively to the outer electrodes 14 a, 14 b and 14 c. The firstsignal S1, the second signal S2, and the third signal S3 are assumed tobe provided as follows. The first signal S1, the second signal S2, andthe third signal S3 take three different arbitrary voltage values ofhigh (H), middle (M) and low (L), and they transit among the threevalues H, M and L at the same clock. Furthermore, at the timing when onesignal takes the value H, one of the remaining two signals takes thevalue M, and the other signal takes the value L. In other words, thefirst signal S1, the second signal S2, and the third signal S3exclusively transit among the three values H, M and L. In that case, atotal of the voltage values of the first signal S1, the second signalS2, and the third signal S3 is substantially always constant at (H+M+L),and a “total” change amount of the voltages due to the transition isalmost zero (0). Accordingly, a “total” change amount of currentsgenerated in the primary coil L1, the secondary coil L2, and thetertiary coil L3 is also almost zero (0), and a change amount ofmagnetic fluxes generated in the electronic component 10 is almost zero“0” (although magnetic flux generated in each of the primary coil L1,the secondary coil L2, and the tertiary coil L3 changes, the changes ofthe magnetic fluxes cancel each other). When there is substantially nochange of the magnetic flux as described above, any impedance issubstantially not generated in the electronic component 10, and hencethe electronic component 10 does not cause any influence upon the firstsignal S1, the second signal S2, and the third signal S3.

On the other hand, with respect to common mode noise, i.e., in-phasenoise contained in the first signal S1, the second signal S2, and thethird signal S3, magnetic fluxes generated in the primary coil L1, thesecondary coil L2, and the tertiary coil L3 are changed in the samedirection, and the changes of the magnetic fluxes do not cancel eachother. Therefore, the electronic component 10 exhibits a large impedancefor the common mode noise. Hence the common mode noise can be reduced inthe electronic component 10. As described above, the primary coil L1,the secondary coil L2, and the tertiary coil L3 constitute a common modefilter, and the electronic component 10 can reduce the common mode noisewithout affecting the first signal S1, the second signal S2, and thethird signal S3. Thus, the electronic component 10 functions as thecommon mode filter for the first signal S1, the second signal S2, andthe third signal S3.

(Manufacturing Method for Electronic Component)

A manufacturing method for the electronic component 10 will be describedbelow with reference to the drawings. The following description is madein connection with an example in which one electronic component 10 ismanufactured. In practice, however, the plurality of electroniccomponents 10 are formed at the same time by laminating mother magneticsubstrates and mother insulator layers, each having a large size, tofabricate a mother body, and by cutting the mother body into a pluralityof pieces.

First, a photosensitive resin, e.g., a polyimide resin, is coated overthe entire upper surface of the magnetic substrate 20 b. Then, thepolyimide resin is exposed in a state blocked off against light with aphotoresist at positions corresponding to the four corners and themiddle of the two long sides of the insulator layer 26 f. As a result,the polyimide resin in a region having been not blocked off againstlight is solidified. After removing the photoresist with an organicsolvent, the polyimide resin is developed to remove the not-solidifiedpolyimide resin and to thermally-solidify the remaining polyimide resin.As a result, the insulator layer 26 f is formed.

Next, an Ag film is formed on the insulator layer 26 f and on themagnetic substrate 20 b, which is exposed from the insulator layer 26 f,by sputtering. Then, a photoresist is formed on regions where the coilconductor layer 30 a, the lead-out conductor layer 40 a, the connectingconductors 70 a to 70 f, and the interlayer connecting conductor v1 areto be formed. Then, the Ag film is removed by etching from a regionexcept for the regions where the coil conductor layer 30 a, the lead-outconductor layer 40 a, the connecting conductors 70 a to 70 f, and theinterlayer connecting conductor v1 are to be formed (i.e., except forthe regions covered with the photoresist). Thereafter, the photoresistis removed with an organic solvent, thus forming the coil conductorlayer 30 a, the lead-out conductor layer 40 a, respective one parts(corresponding to one layer) of the connecting conductors 70 a to 70 f,and the interlayer connecting conductor v1.

The insulator layers 26 a to 26 e, the coil conductor layers 32 a and 34a, the parallel coil conductor layer 36, the lead-out conductor layers42 a, 44 a, 46, 60, 62 and 64, respective remaining parts of theconnecting conductors 70 a to 70 f, and the interlayer connectingconductor v2 and v3 are formed by repeating similar steps to thosedescribed above.

Next, a magnetic paste becoming the magnetic layer 24 is coated over themultilayer body 22, and the magnetic substrate 20 a is pressure-bondedonto the magnetic layer 24.

Next, the six cutouts are formed in the magnetic substrate 20 b by sandblasting. Those cutouts may be formed by laser processing instead of thesand blasting, or by a combination of the sand blasting and the laserprocessing.

Finally, conductor layers are formed on inner peripheral surfaces of thecutouts of the magnetic substrate 20 b with a combination ofelectrolytic plating and photolithography, whereby the connectingportions 16 a to 16 f and the outer electrodes 14 a to 14 f are formed.

(Advantageous Effects)

With the electronic component 10 according to this embodiment, when theelectronic component 10 is mounted to the circuit board 600, adifferential impedance between the tertiary coil L3 and the primary coilL1 (hereinafter referred to as a differential impedance I31) can bematched with a differential impedance between the signal line 604 andthe signal line 608. The following description is made in connectionwith an example in which the primary coil L1 is connected to the signalline 604, the secondary coil L2 is connected to the signal line 606, andthe tertiary coil L3 is connected to the signal line 608.

In the electronic component 10, the parallel coil conductor layer 36 isdisposed. With the provision of the parallel coil conductor layer 36,the differential impedance I31 is made closer to a differentialimpedance between the primary coil L1 and the secondary coil L2(hereinafter referred to as a differential impedance I12) and adifferential impedance between the secondary coil L2 and the tertiarycoil L3 (hereinafter referred to as a differential impedance I23). Inaddition, the interval D2 between the coil conductor layer 34 a and theparallel coil conductor layer 36 is larger than the interval D1 betweenthe coil conductor layer 30 a and the coil conductor layer 32 a and theinterval D1 between the coil conductor layer 32 a and the coil conductorlayer 34 a. Thus, the differential impedance I31 is slightly larger thaneach of the differential impedances I12 and I23. As a result, impedancematching is held between the differential impedance I31 and thedifferential impedance between the signal line 604 and the signal line608. That point will be described in more detail below.

Assuming that an inductance value of the entire electronic component 10including the coils is denoted by L and a capacitance value thereof isdenoted by C when a measurement current (or a differential signal) flowsthrough the electronic component, the differential impedance isexpressed by root of L/C. C includes capacitances between the coilconductor layers (i.e., parasitic capacitances). In the current paths ofthe primary coil L1, the secondary coil L2, and the tertiary coil L3 inthe electronic component 10, the sectional area of the primary coil L1,the sectional area of the secondary coil L2, and the sectional area ofthe tertiary coil L3 are substantially equal to one another.Furthermore, current paths of the primary coil L1, the secondary coilL2, and the tertiary coil L3 are substantially equal to one another inlength and substantially equal in turn numbers. As a result, inductancevalues of the primary coil L1, the secondary coil L2, and the tertiarycoil L3 are substantially equal to one another.

In the electronic component 10, the parallel coil conductor layer 36 isdisposed on the upper side of the coil conductor layer 34 a that isdisposed at the uppermost position among the coil conductor layers 30 a,32 a and 34 a. With such a layout, a capacitance is generated betweenthe coil conductor layer 34 a and the parallel coil conductor layer 36.A capacitance between the primary coil L1 and the secondary coil L2 isformed mainly by the capacitance between the coil conductor layer 30 aand the coil conductor layer 32 a. A capacitance between the secondarycoil L2 and the tertiary coil L3 is formed mainly by the capacitancebetween the coil conductor layer 32 a and the coil conductor layer 34 a.A capacitance between the tertiary coil L3 and the primary coil L1 isformed mainly by the capacitance between the parallel coil conductorlayer 36 and the coil conductor layer 34 a. Thus, C values can be madecloser among the differential impedances I12, I23 and I31. As a result,the differential impedances I12, I23 and I31 come closer to one another.

However, the differential impedance between the signal line 604 and thesignal line 608 is larger than the differential impedance between thesignal line 604 and the signal line 606 and the differential impedancebetween the signal line 606 and the signal line 608. Accordingly, whenthe differential impedance I12 is made matched with the differentialimpedance between the signal line 604 and the signal line 606 and thedifferential impedance I23 is made matched with the differentialimpedance between the signal line 606 and the signal line 608, thedifferential impedance I31 becomes smaller than the differentialimpedance between the signal line 604 and the signal line 608. In such acase, there is a possibility that, due to mismatching between thedifferential impedance I31 and the differential impedance between thesignal line 604 and the signal line 608, a high frequency signal may bereflected and a waveform of the high frequency signal may be distorted.Accordingly, in order to hold matching between the differentialimpedance I31 and the differential impedance between the signal line 604and the signal line 608, it is preferable in some cases to adjust thedifferential impedance I31 such that the differential impedance I31 isslightly larger than the differential impedance I12 and the differentialimpedance I23.

In the electronic component 10, the interval D2 between the coilconductor layer 34 a and the parallel coil conductor layer 36 is largerthan the interval D1 between the coil conductor layer 30 a and the coilconductor layer 32 a and the interval D1 between the coil conductorlayer 32 a and the coil conductor layer 34 a. Therefore, the capacitancegenerated between the tertiary coil L3 and the primary coil L1 becomessmaller than the capacitance generated between the primary coil L1 andthe secondary coil L2 and the capacitance generated between thesecondary coil L2 and the tertiary coil L3. Thus, the differentialimpedance I31 becomes slightly larger than each of the differentialimpedances I12 and I23. As a result, impedance matching is held betweenthe differential impedance I31 and the differential impedance betweenthe signal line 604 and the signal line 608.

Moreover, in the electronic component 10, degradation of Sdd21 in a highfrequency band is suppressed. “Sdd21” implies bandpass characteristicsof a differential mode signal. In the following description, Sdd21between the primary coil L1 and the secondary coil L2 is called bandpasscharacteristics S12, Sdd21 between the secondary coil L2 and thetertiary coil L3 is called bandpass characteristics S23, and Sdd21between the tertiary coil L3 and the primary coil L1 is called bandpasscharacteristics S31.

In the electronic component 10, the provision of the parallel coilconductor layer 36 increases the capacitance generated between thetertiary coil L3 and the primary coil L1 in comparison with anelectronic component in which the parallel coil conductor layer 36 isnot disposed. If the capacitance generated between the tertiary coil L3and the primary coil L1 increases, the bandpass characteristics S31 maydegrade.

To cope with the above point, in the electronic component 10, theinterval D2 between the coil conductor layer 34 a and the parallel coilconductor layer 36 is set larger than the interval D1 between the coilconductor layer 30 a and the coil conductor layer 32 a and the intervalD1 between the coil conductor layer 32 a and the coil conductor layer 34a. Therefore, the capacitance generated between the tertiary coil L3 andthe primary coil L1 becomes smaller than the capacitance generatedbetween the primary coil L1 and the secondary coil L2 and thecapacitance generated between the secondary coil L2 and the tertiarycoil L3. As a result, the degradation of the bandpass characteristicsS31 is suppressed.

Moreover, according to the electronic component 10, as described above,in the current paths of the primary coil L1, the secondary coil L2, andthe tertiary coil L3, the sectional area of the primary coil L1, thesectional area of the secondary coil L2, and the sectional area of thetertiary coil L3 are substantially equal to one another. As a result,the resistance value of the primary coil L1, the resistance value of thesecondary coil L2, and the resistance value of the tertiary coil L3 aresubstantially equal to one another. Thus, respective values of currentsflowing through the primary coil L1, the secondary coil L2, and thetertiary coil L3 can be made closer to one another, and respectiveamounts of heat generated from the primary coil L1, the secondary coilL2, and the tertiary coil L3 can also be made closer to one another.

When the resistance value of the primary coil L1, the resistance valueof the secondary coil L2, and the resistance value of the tertiary coilL3 are substantially equal to one another, directivity of the electroniccomponent 10 is eliminated. This implies that the outer electrodes 14 ato 14 c may be used as the input terminals and the outer electrodes 14 dto 14 f may be used as the output terminals, or that the outerelectrodes 14 a to 14 c may be used as the output terminals and theouter electrodes 14 d to 14 f may be used as the input terminals. As aresult, in the electronic component 10, it is no longer required toidentify the orientation of the electronic component when it is mounted,and to attach an orientation identification mark.

According to the electronic component 10, an amount of heat generatedfrom the coil conductor layer 30 a can be made closer to that generatedfrom the parallel coil conductor layer 36. To explain in more detail,the sectional area of the coil conductor layer 30 a is substantiallyequal to that of the parallel coil conductor layer 36. In addition, thelength of the coil conductor layer 30 a is substantially equal to thatof the parallel coil conductor layer 36. Therefore, the resistance valueof the coil conductor layer 30 a is substantially equal to that of theparallel coil conductor layer 36. Moreover, since the coil conductorlayer 30 a and the parallel coil conductor layer 36 are electricallyconnected in parallel, voltages applied to the coil conductor layer 30 aand the parallel coil conductor layer 36 are substantially equal to eachother, and currents flowing through the coil conductor layer 30 a andthe parallel coil conductor layer 36 are also substantially equal toeach other. Hence the amount of heat generated from the coil conductorlayer 30 a can be made closer to that generated from the parallel coilconductor layer 36.

According to the electronic component 10, the interval D1 between thetwo coil conductor layers 30 a and 32 a adjacent in the up-downdirection, and the interval D1 between the two coil conductor layer 32 aand 34 a adjacent in the up-down direction are substantially equal toeach other. Therefore, conditions in laminating the coil conductorlayers 30 a, 32 a and 34 a can be made uniform, and reliability of theelectronic component 10 can be improved. In addition, since the coilconductor layers 30 a, 32 a and 34 a can be formed under the sameconditions, manufacturing steps are rationalized.

According to the electronic component 10, a return loss can be reduced.To explain in more detail, in the circuit board 600, a combination ofthe signal lines, which increases the differential impedancetherebetween, is the combination of the signal line 604 and the signalline 608. The signal line 604 and the signal line 608 are arranged onboth sides of the signal line 606. On the other hand, in the electroniccomponent 10, coils for which the differential impedance is to beadjusted are the primary coil L1 and the tertiary coil L3. Therefore,the electronic component 10 is preferably constituted such that thesignal line 604 can be easily connected to the primary coil L1 and thesignal line 608 can be easily connected to the tertiary coil L3. Inconsideration of the above point, the outer electrode 14 d connected tothe primary coil L1, the outer electrode 14 e connected to the secondarycoil L2, and the outer electrode 14 f connected to the tertiary coil L3are arrayed to position in the mentioned order from the rear side towardthe front side. In other words, the outer electrodes 14 d and 14 f arearranged on both sides of the outer electrode 14 e. Thus, thedifferential impedance between the primary coil L1 and the tertiary coilL3 can be adjusted to be matched with the differential impedance betweenthe signal line 604 and the signal line 608. As a result, the returnloss can be reduced in the electronic component 10.

The inventors of this application conducted computer simulations,described below, with intent to clarify that the differential impedanceI31 can be adjusted to a proper level in the electronic component 10. Toexplain in more detail, a model having the same structure as theelectronic component 10 was fabricated as a first model according to theembodiment. A model not including the parallel coil conductor layer 36in the electronic component 10 was fabricated as a second modelaccording to a comparative example. The differential impedances I12, I23and I31 were computed for each of the first model and the second model.The computation was executed such that, when computing the differentialimpedance I12, for example, a differential signal was input to each ofthe primary coil L1 and the secondary coil L2, and the tertiary coil L3was terminated at 50Ω relative to a ground potential.

FIG. 4 is a graph representing a simulation result of the first model.FIG. 5 is a graph representing a simulation result of the second model.In FIGS. 4 and 5, the vertical axis indicates differential impedance,and the horizontal axis indicates frequency.

As seen from FIG. 5, in the second model, the differential impedance I31is much larger than the differential impedances I12 and I23. At 1 GHz,for example, the differential impedance I31 is 145Ω, whereas thedifferential impedances I12 and I23 are each 85Ω.

On the other hand, as seen from FIG. 4, in the first model, thedifferential impedance I31 is slightly larger than the differentialimpedances I12 and I23. At 1 GHz, for example, the differentialimpedance I31 is 100Ω, whereas the differential impedances I12 and I23are each 75Ω. It is hence understood that, in the electronic component10, the differential impedance I31 can be adjusted to a proper level.

The inventors of this application further conducted computersimulations, described below, with intent to clarify that thedegradation of Sdd21 in the high frequency band can be suppressed in theelectronic component 10. To explain in more detail, the bandpasscharacteristics S12, S23 and S31 were computed for each of the firstmodel and the second model. The computation was executed such that, whencomputing the bandpass characteristics S12, for example, a differentialsignal was input to each of the primary coil L1 and the secondary coilL2, and the tertiary coil L3 was terminated at 50Ω relative to a groundpotential.

FIG. 6A is a graph representing a simulation result of the first model.FIG. 6B is a graph representing a simulation result of the second model.In FIGS. 6A and 6B, the vertical axis indicates bandpasscharacteristics, and the horizontal axis indicates frequency.

As seen from comparing FIGS. 6A and 6B, comparatively close results areobtained for both S31 of the first model and S31 of the second model. Itis hence understood that the degradation of Sdd21 (particularly thebandpass characteristics S31) in a high frequency band can be suppressedin the electronic component 10 according to this embodiment.

(First Modification)

A configuration of an electronic component 10 a according to a firstmodification will be described below with reference to the drawings.FIG. 7A is a schematic view illustrating a positional relationship amongthe coil conductor layers 30 a, 32 a and 34 a and the parallel coilconductor layer 36 of the electronic component 10. FIG. 7B is aschematic view illustrating a positional relationship among coilconductor layers 30 a, 32 a, 34 a, 30 b, 32 b and 34 b and a parallelcoil conductor layer 36 of the electronic component 10 a.

In the electronic component 10, the primary coil L1 includes one coilconductor layer 30 a and one parallel coil conductor layer 36, thesecondary coil L2 includes one coil conductor layer 32 a, and thetertiary coil L3 includes one coil conductor layer 34 a. On the otherhand, in the electronic component 10 a, the primary coil L1 includes twocoil conductor layers 30 a and 30 b and one parallel coil conductorlayer 36, the secondary coil L2 includes two coil conductor layers 32 aand 32 b, and the tertiary coil L3 includes two coil conductor layers 34a and 34 b. Thus, the electronic component 10 and the electroniccomponent 10 a are different from each other in arrangement of the coilconductor layers 30 a, 32 a, 34 a, 30 b, 32 b and 34 b and the parallelcoil conductor layer 36, as described below.

In the electronic component 10, as illustrated in FIG. 7A, one coilconductor layer 30 a, one coil conductor layer 32 a, and one coilconductor layer 34 a are arrayed in the mentioned order from the lowerside toward the upper side and constitute a coil conductor layer groupGa. The parallel coil conductor layer has the same shape as the coilconductor layer 30 a. The parallel coil conductor layer 36 iselectrically connected to the coil conductor layer 30 a in parallel andis disposed on the upper side of the coil conductor layer 34 a that isdisposed at the uppermost position.

On the other hand, in the electronic component 10 a, as illustrated inFIG. 7B, one coil conductor layer group Ga is constituted by one coilconductor layer 30 a, one coil conductor layer 32 a, and one coilconductor layer 34 a, which are arrayed in the mentioned order from thelower side toward the upper side. One coil conductor layer 30 b, onecoil conductor layer 32 b, and one coil conductor layer 34 b are arrayedin the mentioned order from the lower side toward the upper side andconstitute another coil conductor layer group Gb. The coil conductorlayer groups Ga and Gb are arrayed in the mentioned order from the lowerside toward the upper side. The parallel coil conductor layer 36 has thesame shape as the coil conductor layer 30 b. The parallel coil conductorlayer 36 is electrically connected to the coil conductor layer 30 b inparallel and is disposed on the upper side of the coil conductor layer34 b that is disposed at the uppermost position.

A configuration of the electronic component 10 a will be described inmore detail below with reference to the drawings. FIG. 8A is an explodedperspective view of a multilayer body 22 of the electronic component 10a. In FIG. 8A, however, an insulator layer 26 a is omitted. FIG. 8B is asectional structural view, taken along 3-3, of the electronic component10 a illustrated in FIG. 1. FIG. 1 is further referenced for an externalperspective view of the electronic component 10 a.

Outer electrodes 14 a to 14 f, connecting portions 16 a to 16 f,magnetic substrates 20 a and 20 b, and a magnetic layer 24 of theelectronic component 10 a are similar to the outer electrodes 14 a to 14f, the connecting portions 16 a to 16 f, the magnetic substrates 20 aand 20 b, and the magnetic layer 24 of the electronic component 10,respectively, and hence description of those members is omitted here.

The multilayer body 22 includes insulator layers 26 a to 26 h, and ithas a substantially rectangular shape in the plan view. Shapes andmaterials of the insulator layers 26 a to 26 h in the electroniccomponent 10 a are similar to those of the insulator layers 26 a to 26 fin the electronic component 10, and hence description of the shapes andthe materials thereof is omitted here. However, it is to be noted thatthe insulator layer 26 b has a larger thickness than each of theinsulator layers 26 a and 26 c to 26 h.

The primary coil L1 is disposed inside the multilayer body 22 andincludes the coil conductor layer 30 a, the coil conductor layer 30 b,and an interlayer connecting conductor v11. The coil conductor layer 30a in the electronic component 10 a is similar to the coil conductorlayer 30 a in the electronic component 10 except for being disposed onthe upper surface of the insulator layer 26 h, and hence description ofthe coil conductor layer 32 a is omitted here. A lead-out portion 50 inthe electronic component 10 a is similar to the lead-out portion in theelectronic component 10 except that a lead-out conductor layer 40 a isdisposed on the upper surface of the insulator layer 26 h, and hencedescription of the lead-out portion 50 is omitted here.

The coil conductor layer 30 b is disposed on the upper surface of theinsulator layer 26 e, and it has a substantially spiral shape extendingfrom the inner peripheral side toward the outer peripheral side whilecircling clockwise in the plan view. In this embodiment, the coilconductor layer 30 b has a length corresponding to about four times thecircumference of the spiral shape. The center of the coil conductorlayer 30 b is substantially aligned with the center (crossed point ofdiagonal lines) of the electronic component 10 a in the plan view.

The interlayer connecting conductor v11 is a conductor penetratingthrough the insulator layers 26 b to 26 h in the up-down direction, andit has a substantially linear shape extending in the left-rightdirection in the plan view. The interlayer connecting conductor v11 isdisposed in rear half regions of the insulator layers 26 b to 26 h inthe plan view, and it connects an end portion of the coil conductorlayer 30 a on the inner peripheral side and an end portion of the coilconductor layer 30 b on the inner peripheral side.

A lead-out portion 53′ connects the other end of the primary coil L1(i.e., an end portion of the coil conductor layer 30 b on the outerperipheral side) to the outer electrode 14 d, and it does not have thesubstantially spiral shape in the plan view, as illustrated in FIG. 8A.The lead-out portion 53′ includes a lead-out conductor layer 40 b and aconnecting conductor 70 d. The connecting conductor 70 d is a conductorhaving a substantially triangular prism shape and disposed at rear rightcorners of the insulator layers 26 b to 26 h. The connecting conductor70 d extends in the up-down direction from the upper surface of theinsulator layer 26 b to the bottom surface of the insulator layer 26 h,and is connected at its lower end to the connecting portion 16 d.

The lead-out conductor layer 40 b is disposed on the upper surface ofthe insulator layer 26 e, and is connected to the end portion of thecoil conductor layer 30 b on the outer peripheral side and further tothe connecting conductor 70 d. The lead-out conductor layer 40 b doesnot have the substantially spiral shape in the plan view, and it extendsrightward from the end portion of the coil conductor layer 30 b on theouter peripheral side. With such an arrangement, the other end of theprimary coil L1 (i.e., the end portion of the coil conductor layer 30 bon the outer peripheral side) and the outer electrode 14 d are connectedto each other through the lead-out portion 53′ (including the lead-outconductor layer 40 b and the connecting conductor 70 d) and theconnecting portion 16 d.

The secondary coil L2 is disposed inside the multilayer body 22 andincludes the coil conductor layer 32 a, the coil conductor layer 32 b,and an interlayer connecting conductor v12. The coil conductor layer 32a in the electronic component 10 a is similar to the coil conductorlayer 32 a in the electronic component 10 except for being disposed onthe upper surface of the insulator layer 26 g, and hence description ofthe coil conductor layer 32 a is omitted here. A lead-out portion 51 inthe electronic component 10 a is similar to the lead-out portion in theelectronic component 10 except that a lead-out conductor layer 42 a isdisposed on the upper surface of the insulator layer 26 g, and hencedescription of the lead-out portion 51 is omitted here.

The coil conductor layer 32 b is disposed on the upper surface of theinsulator layer 26 d, and it has a substantially spiral shape extendingfrom the inner peripheral side toward the outer peripheral side whilecircling clockwise in the plan view. In this embodiment, the coilconductor layer 32 b has a length corresponding to about four times thecircumference of the spiral shape. The center of the coil conductorlayer 32 b is substantially aligned with the center (crossed point ofthe diagonal lines) of the electronic component 10 a in the plan view.

As illustrated in FIG. 8A, the coil conductor layer 32 b overlaps thecoil conductor layer 30 b substantially over the entire length in theplan view. Therefore, the coil conductor layer 30 b (i.e., the primarycoil L1) and the coil conductor layer 32 b (i.e., the secondary coil L2)are magnetically coupled to each other. However, positions of both endsof the coil conductor layer 30 b and positions of both ends of the coilconductor layer 32 b are set to be different such that the lead-outportions 50 and 53′ and later-described lead-out portions 51 and 54′ donot interfere with each other. More specifically, the end portion of thecoil conductor layer 32 b on the outer peripheral side is positioneddownstream of the end portion of the coil conductor layer 30 b on theouter peripheral side in the clockwise direction. The end portion of thecoil conductor layer 32 b on the inner peripheral side is positioneddownstream of the end portion of the coil conductor layer 30 b on theinner peripheral side in the clockwise direction. With such anarrangement, the length of the coil conductor layer 30 b and the lengthof the coil conductor layer 32 b are substantially equal to each other.

The interlayer connecting conductor v12 is a conductor penetratingthrough the insulator layers 26 d to 26 g in the up-down direction, andit has a substantially linear shape extending in the left-rightdirection in the plan view. The interlayer connecting conductor v12 isdisposed in central regions of the insulator layers 26 d to 26 g in theplan view, and it connects the end portion of the coil conductor layer32 a on the inner peripheral side and the end portion of the coilconductor layer 32 b on the inner peripheral side.

A lead-out portion 54′ connects the other end of the secondary coil L2(i.e., an end portion of the coil conductor layer 32 b on the outerperipheral side) to the outer electrode 14 e, and it does not have thesubstantially spiral shape in the plan view, as illustrated in FIG. 8A.The lead-out portion 54′ includes a lead-out conductor layer 42 b and aconnecting conductor 70 e. The connecting conductor 70 e is a conductorhaving a substantially quadrangular prism shape and is disposed at themiddle of the long sides of the insulator layers 26 b to 26 h on theright side. The connecting conductor 70 e extends in the up-downdirection from the upper surface of the insulator layer 26 b to thebottom surface of the insulator layer 26 h, and is connected at itslower end to the connecting portion 16 e.

The lead-out conductor layer 42 b is disposed on the upper surface ofthe insulator layer 26 d, and is connected to the end portion of thecoil conductor layer 32 b on the outer peripheral side and further tothe connecting conductor 70 e. The lead-out conductor layer 42 b doesnot have the substantially spiral shape in the plan view, and it extendsrightward from the end portion of the coil conductor layer 32 b on theouter peripheral side. With such an arrangement, the other end of thesecondary coil L2 (i.e., the end portion of the coil conductor layer 32b on the outer peripheral side) and the outer electrode 14 e areconnected to each other through the lead-out portion 54′ (including thelead-out conductor layer 42 b and the connecting conductor 70 e) and theconnecting portion 16 e.

The tertiary coil L3 is disposed inside the multilayer body 22 andincludes the coil conductor layer 34 a, the coil conductor layer 34 b,and an interlayer connecting conductor v13. The coil conductor layer 34a in the electronic component 10 a is similar to the coil conductorlayer 34 a in the electronic component 10 except for being disposed onthe upper surface of the insulator layer 26 f, and hence description ofthe coil conductor layer 34 a is omitted here. A lead-out portion 52 inthe electronic component 10 a is similar to the lead-out portion in theelectronic component 10 except that a lead-out conductor layer 44 a isdisposed on the upper surface of the insulator layer 26 f, and hencedescription of the lead-out portion 52 is omitted here.

The coil conductor layer 34 b is disposed on the upper surface of theinsulator layer 26 c, and it has a substantially spiral shape extendingfrom the inner peripheral side toward the outer peripheral side whilecircling clockwise in the plan view. In this embodiment, the coilconductor layer 34 b has a length corresponding to about four times thecircumference of the spiral shape. The center of the coil conductorlayer 34 b is substantially aligned with the center (crossed point ofthe diagonal lines) of the electronic component 10 a in the plan view.

As illustrated in FIG. 8A, the coil conductor layer 34 b overlaps thecoil conductor layers 30 b and 32 b substantially over the entire lengthin the plan view. Therefore, the coil conductor layer 30 b (i.e., theprimary coil L1), the coil conductor layer 32 b (i.e., the secondarycoil L2) and the coil conductor layer 34 b (i.e., the tertiary coil L3)are magnetically coupled to one another. However, positions of both endsof the coil conductor layer 30 b, positions of both ends of the coilconductor layer 32 b, and positions of both ends of the coil conductorlayer 34 b are set to be different such that the lead-out portions 50and 53′, the lead-out portions 51 and 54′, and lead-out portions 52 and55′ do not interfere with one another. More specifically, the endportion of the coil conductor layer 34 b on the outer peripheral side ispositioned downstream of the end portions of the coil conductor layers30 b and 32 b on the outer peripheral side in the clockwise direction.The end portion of the coil conductor layer 34 b on the inner peripheralside is positioned downstream of the end portions of the coil conductorlayers 30 b and 32 b on the inner peripheral side in the clockwisedirection. With such an arrangement, the length of the coil conductorlayer 30 b, the length of the coil conductor layer 32 b, and the lengthof the coil conductor layer 34 b are substantially equal to one another.

The interlayer connecting conductor v13 is a conductor penetratingthrough the insulator layers 26 c to 26 f in the up-down direction, andit has a substantially linear shape extending in the left-rightdirection in the plan view. The interlayer connecting conductor v13 isdisposed in front half regions of the insulator layers 26 c to 26 f inthe plan view, and it connects the end portion of the coil conductorlayer 34 a on the inner peripheral side and the end portion of the coilconductor layer 34 b on the inner peripheral side.

A lead-out portion 55′ connects the other end of the tertiary coil L3(i.e., an end portion of the coil conductor layer 34 b on the outerperipheral side) to the outer electrode 14 f, and it does not have thesubstantially spiral shape in the plan view, as illustrated in FIG. 8A.The lead-out portion 55′ includes a lead-out conductor layer 44 b and aconnecting conductor 70 f. The connecting conductor 70 f is a conductorhaving a substantially triangular prism shape and disposed at frontright corners of the insulator layers 26 b to 26 h. The connectingconductor 70 f extends in the up-down direction from the upper surfaceof the insulator layer 26 b to the bottom surface of the insulator layer26 h, and is connected at its lower end to the connecting portion 16 f.

The lead-out conductor layer 44 b is disposed on the upper surface ofthe insulator layer 26 c, and is connected to the end portion of thecoil conductor layer 34 b on the outer peripheral side and further tothe connecting conductor 70 f. The lead-out conductor layer 44 b doesnot have the substantially spiral shape in the plan view, and it extendsforward from the end portion of the coil conductor layer 34 b on theouter peripheral side. With such an arrangement, the other end of thetertiary coil L3 (i.e., the end portion of the coil conductor layer 34 bon the outer peripheral side) and the outer electrode 14 f are connectedto each other through the lead-out portion 55′ (including the lead-outconductor layer 44 b and the connecting conductor 70 f) and theconnecting portion 16 f.

The primary coil L1 further includes a parallel coil conductor layer 36,one example of the parallel primary coil conductor layer. The parallelcoil conductor layer 36 has the same shape as the coil conductor layer30 b. The parallel coil conductor layer 36 is electrically connected tothe coil conductor layer 30 b in parallel, and is disposed on the upperside of the coil conductor layer 34 b that is disposed at an uppermostposition among the coil conductor layers 30 a, 32 a, 34 a, 30 b, 32 band 34 b. The parallel coil conductor layer 36 is disposed on the uppersurface of the insulator layer 26 b, and has a substantially spiralshape extending from the inner peripheral side toward the outerperipheral side while circling clockwise in the plan view. In thisembodiment, the parallel coil conductor layer 36 has a lengthcorresponding to about four times the circumference of the spiral shape.The center of the parallel coil conductor layer 36 is substantiallyaligned with the center (crossed point of the diagonal lines) of theelectronic component 10 a in the plan view.

An end portion of the parallel coil conductor layer 36 on the innerperipheral side is connected to the end portions of the coil conductorlayers 30 a and 30 b on the inner peripheral side through the interlayerconnecting conductor v11.

A lead-out portion 56′ connects an end portion of the parallel coilconductor layer 36 on the outer peripheral side to the outer electrode14 d, and it does not have the substantially spiral shape in the planview, as illustrated in FIG. 8A. The lead-out portion 56′ includes alead-out conductor layer 46′ and the connecting conductor 70 d. Thelead-out conductor layer 46′ is disposed on the upper surface of theinsulator layer 26 b, and is connected to the end portion of theparallel coil conductor layer 36 on the outer peripheral side andfurther to the connecting conductor 70 d. The lead-out conductor layer46′ does not have the substantially spiral shape in the plan view, andit extends rightward from the end portion of the parallel coil conductorlayer 36 on the outer peripheral side. With such an arrangement, the endportion of the parallel coil conductor layer 36 on the outer peripheralside and the outer electrode 14 d are connected to each other throughthe lead-out portion 56′ (including the lead-out conductor layer 46′ andthe connecting conductor 70 d) and the connecting portion 16 d. Thus,the parallel coil conductor layer 36 is electrically connected to thecoil conductor layer 30 b in parallel.

As illustrated in FIG. 8B, respective line widths of the coil conductorlayers 30 a, 32 a, 34 a, 30 b, 32 b and 34 b and a line width of theparallel coil conductor layer 36 are substantially equal to one anotheras denoted by a line width w1. However, each of the coil conductorlayers 30 a, 32 a, 34 a, 32 b and 34 b has a thickness d1, and each ofthe coil conductor layer 30 b and the parallel coil conductor layer 36has a thickness d2. The thickness d2 is about a half of the thicknessd1. Accordingly, a total of a sectional area of the coil conductor layer30 b, one example of a predetermined primary coil conductor layer, and asectional area of the parallel coil conductor layer 36 is substantiallyequal to a sectional area of the coil conductor layer 30 a, one exampleof each of the primary coil conductor layers other than thepredetermined primary coil conductor layer, a sectional area of each ofthe coil conductor layers 32 a and 32 b, and a sectional area of each ofthe coil conductor layers 34 a and 34 b.

Moreover, thicknesses of the insulator layers 26 a and 26 c to 26 h areeven. Therefore, intervals D1 between two coil conductor layers amongthe coil conductor layers 30 a, 32 a, 34 a, 30 b, 32 b and 34 b, everytwo of those being adjacent to each other in the up-down direction, aresubstantially the same. However, the insulator layer 26 b has a largerthickness than each of the insulator layers 26 a and 26 c to 26 h.Accordingly, an interval D3 between the parallel coil conductor layer 36and the coil conductor layer 34 b is larger than the interval D1 betweenevery two among the coil conductor layers 30 a, 32 a, 34 a, 30 b, 32 band 34 b adjacent to each other in the up-down direction.

The electronic component 10 a having the above-described configurationcan also provide similar advantageous effects to those obtained with theelectronic component 10. Stated in another way, the configurationproviding uneven intervals between adjacent two insulator layers amongthe insulator layers may be implemented by inserting the lead-outconductor layer as in the electronic component 10, or by changing thethickness of the insulator layer as in the electronic component 10 a.

In the electronic component 10 a, a higher inductance value can beobtained for the following reason. The reason is described by taking theprimary coil L1 as an example. The primary coil L1 includes the coilconductor layers 30 a and 30 b and the interlayer connecting conductorv11. The coil conductor layer 30 a has the substantially spiral shapeextending from the outer peripheral side toward the inner peripheralside while circling clockwise. The coil conductor layer 30 b has thesubstantially spiral shape extending from the inner peripheral sidetoward the outer peripheral side while circling clockwise. Theinterlayer connecting conductor v11 connects the end portion of the coilconductor layer 30 a on the inner peripheral side and the end portion ofthe coil conductor layer 30 b on the inner peripheral side. Thus, sincethe primary coil L1 of the electronic component 10 a is constituted bythe two coil conductor layers 30 a and 30 b connected in series, it hasa higher inductance value than the primary coil L1 of the electroniccomponent 10.

Furthermore, in the electronic component 10 a, the lead-out conductorlayers 60, 62 and 64 are no longer required. The reason is described bytaking the primary coil L1 as an example. The end portion of the coilconductor layer 30 a on the inner peripheral side and the end portion ofthe coil conductor layer 30 b on the inner peripheral side are connectedby the interlayer connecting conductor v11. The end portion of the coilconductor layer 30 a on the outer peripheral side is connected to theconnecting conductor 70 a through the lead-out conductor layer 40 a thatis disposed on the insulator layer 26 h on which the coil conductorlayer 30 a is also disposed. The end portion of the coil conductor layer30 b on the outer peripheral side is connected to the connectingconductor 70 d through the lead-out conductor layer 40 b that isdisposed on the insulator layer 26 e on which the coil conductor layer30 b is also disposed. Accordingly, the lead-out conductor layer 60,which is disposed in the electronic component 10 on the insulator layer26 b different from the insulator layers 26 e and 26 h, is no longerrequired in the electronic component 10 a.

While the electronic component 10 a has been described above asincluding the two coil conductor layer groups Ga and Gb, it may includemore than two coil conductor layer groups. The following description ismade in connection with the case where the electronic component 10 aincludes n coil conductor layer groups Ga, Gb, etc. n is a naturalnumber.

When the electronic component 10 a includes n coil conductor layergroups Ga, Gb, etc., the primary coil L1 includes n coil conductorlayers 30 a, 30 b, etc. and the parallel coil conductor layer 36, thesecondary coil L2 includes n coil conductor layers 32 a, 32 b, etc., andthe tertiary coil L3 includes n coil conductor layers 34 a, 34 b, etc.The coil conductor layer 30 a, 32 a and 34 a are arrayed one by one inthe mentioned order from the lower side toward the upper side andconstitute a coil conductor layer group Ga. The coil conductor layer 30b, 32 b and 34 b are arrayed one by one in the mentioned order from thelower side toward the upper side and constitute a coil conductor layergroup Gb. The other coil conductor layer groups subsequent to the coilconductor layer group Gc are also each constituted similarly to the coilconductor layer groups Ga and Gb. The n coil conductor layer groups Ga,Gb, etc. are arrayed in the mentioned order from the lower side towardthe upper side.

The parallel coil conductor layer 36 has the same shape as apredetermined coil conductor layer, one example of a predeterminedprimary coil conductor layer, among the n coil conductor layers 30 a, 30b, etc., and it is electrically connected to the predetermined one amongthe number n of coil conductor layers 30 a, 30 b, etc. in parallel. Inaddition, the parallel coil conductor layer 36 is disposed on the upperside of the coil conductor layer (one example of the predeterminedtertiary coil conductor layer), which is disposed at an uppermostposition among the n coil conductor layers 34 a, 34 b, etc.

An interval in the up-down direction between the parallel coil conductorlayer 36 and the coil conductor layer, which is disposed at theuppermost position among the n coil conductor layers 34 a, 34 b, etc.,is larger than an interval between every two among the n coil conductorlayers 30 a, 30 b, etc., among the n coil conductor layers 32 a, 32 b,etc., and among the n coil conductor layers 34 a, 34 b, etc., the twobeing adjacent to each other in the up-down direction.

The following description is made in connection with the case where n isan even number. In this case, the n coil conductor layers 30 a, 30 b,etc. in the primary coil L1 includes n/2 coil conductor layers 30 a, 30c, 30 e, etc. each of which has a substantially spiral shape extendingfrom the outer peripheral side toward the inner peripheral side whilecircling clockwise in the plan view, and the n/2 coil conductor layers30 b, 30 d, 30 f, etc. each of which has a substantially spiral shapeextending from the inner peripheral side toward the outer peripheralside while circling clockwise in the plan view. The primary coil L1 isconstituted by alternately electrically connecting the n/2 coilconductor layers 30 a, 30 c, 30 e, etc. and the n/2 coil conductorlayers 30 b, 30 d, 30 f, etc. in series. With such an arrangement, thelead-out conductor layer 60 is no longer required.

(Second Modification)

A configuration of an electronic component 10 b according to a secondmodification will be described below with reference to the drawings.FIG. 9 is a schematic view illustrating a positional relation among coilconductor layers 30 a-1, 30 a-2, 32 a, 34 a, 30 b, 32 b-1, 32 b-2, 34b-1 and 34 b-2 and a parallel coil conductor layer 36 of the electroniccomponent 10 b.

In the electronic component 10 a, as illustrated in FIG. 7B, the coilconductor layer 30 b and the parallel coil conductor layer 36 areelectrically connected in parallel. On the other hand, in the electroniccomponent 10 b, as illustrated in FIG. 9, the coil conductor layer 30a-1 and the coil conductor layer 30 a-2 are electrically connected inparallel, the coil conductor layer 32 b-1 and the coil conductor layer32 b-2 are electrically connected in parallel, and the coil conductorlayer 34 b-1 and the coil conductor layer 34 b-2 are electricallyconnected in parallel. Thus, the coil conductor layers may be connectedin parallel at a plurality of locations.

(Third Modification)

A configuration of an electronic component 10 c according to a thirdmodification will be described below with reference to the drawings.FIG. 10 is a sectional structural view, taken along 3-3, of theelectronic component 10 c illustrated in FIG. 1. FIGS. 1 and 2 arefurther referenced for an external perspective view and an explodedperspective view of the electronic component 10 c.

The electronic component 10 c is different from the electronic component10 in the thicknesses of the coil conductor layers 30 a, 32 a and 34 aand the parallel coil conductor layer 36. To explain in more detail, inthe electronic component 10, as illustrated in FIG. 3, each of the coilconductor layer 30 a and the parallel coil conductor layer 36 has thethickness d2, and each of the coil conductor layers 32 a and 34 a hasthe thickness d1. The thickness d2 is about half of the thickness d1. Asa result, the total of the sectional area of the coil conductor layer 30a and the sectional area of the parallel coil conductor layer 36 issubstantially equal to the sectional area of the coil conductor layer 32a and the sectional area of the coil conductor layer 34 a.

On the other hand, in the electronic component 10 c, as illustrated inFIG. 10, each of the coil conductor layer 32 a and the coil conductorlayer 34 a has the thickness d1, the coil conductor layer 30 a has athickness d3, and the parallel coil conductor layer 36 has a thicknessd4. In FIG. 10, the thickness d4 is about ⅓ of the thickness d3. Thus,the thickness of the coil conductor layer 30 a and the thickness of theparallel coil conductor layer 36 may be different from each other.However, a total of the thickness d3 and the thickness d4 issubstantially equal to the thickness d1. As a result, the total of thesectional area of the coil conductor layer 30 a and the sectional areaof the parallel coil conductor layer 36 is substantially equal to thesectional area of the coil conductor layer 32 a and the sectional areaof the coil conductor layer 34 a.

The electronic component 10 c having the above-described configurationcan also provide similar advantageous effects to those obtained with theelectronic component 10.

It is to be noted that, in the electronic component 10 c, the thicknessd4 may be larger than the thickness d3.

(Fourth Modification)

A configuration of an electronic component 10 d according to a fourthmodification will be described below with reference to the drawings.FIG. 11 is a sectional structural view, taken along 3-3, of theelectronic component 10 d illustrated in FIG. 1. FIG. 1 is furtherreferenced for an external perspective view of the electronic component10 d.

The electronic component 10 d is different from the electronic component10 in that the parallel coil conductor layer 36 is not disposed, and theinterval between the coil conductor layer 30 a and the coil conductorlayer 32 a is different from the interval between the coil conductorlayer 32 a and the coil conductor layer 34 a.

The coil conductor layers 30 a, 32 a and 34 a are arrayed to position inthe mentioned order from the lower side toward the upper side and aremagnetically coupled to constitute a common mode filter. Intervalsbetween two of the coil conductor layer 30 a, the coil conductor layer32 a, and the coil conductor layer 34 a, every two of those beingadjacent to each other in the up-down direction, are not even. In theelectronic component 10 d, an interval D11 between the coil conductorlayer 30 a and the coil conductor layer 32 a is larger than an intervalD12 between the coil conductor layer 32 a and the coil conductor layer34 a.

In the electronic component 10, the parallel coil conductor layer 36 isdisposed to make the differential impedance I31 closer to thedifferential impedance I12 and the differential impedance I23. Theinterval D2 between the coil conductor layer 34 a and the parallel coilconductor layer 36 is larger than the interval D1 between the coilconductor layer 30 a and the coil conductor layer 32 a and the intervalD1 between the coil conductor layer 32 a and the coil conductor layer 34a. As a result, the differential impedance I31 is slightly larger thaneach of the differential impedances I12 and I23.

On the other hand, in the electronic component 10 d, since the parallelcoil conductor layer 36 is not disposed, the differential impedance I12,the differential impedance I23, and the differential impedance I31 arenot made closer to one another unlike the electronic component 10. Thus,the differential impedance I31 is larger than each of the differentialimpedances I12 and I23. In such a state, the interval D11 between thecoil conductor layer 30 a and the coil conductor layer 32 a is largerthan the interval D12 between the coil conductor layer 32 a and the coilconductor layer 34 a. Therefore, the differential impedance I12 islarger than the differential impedance I23. As a result, thedifferential impedance I31 is maximal, and the differential impedanceI23 is minimal.

Thus, in the electronic component 10 d, the parallel coil conductorlayer 36 is not essential. To explain in more detail, in the circuitboard 600 illustrated in FIG. 13, the differential impedance between thesignal line 604 and the signal line 608 is larger than the differentialimpedance between the signal line 604 and the signal line 606 and thedifferential impedance between the signal line 606 and the signal line608. Depending on structures of the circuit board 600, however, there isa case, for example, that the differential impedance between the signalline 604 and the signal line 608 is maximal and the differentialimpedance between the signal line 606 and the signal line 608 isminimal. In the circuit board 600 of that type, matching of thedifferential impedance is held by mounting the electronic component 10d.

Depending on structures of the circuit board 600, the interval D11between the coil conductor layer 30 a and the coil conductor layer 32 amay be smaller than the interval D12 between the coil conductor layer 32a and the coil conductor layer 34 a.

(Other Embodiments)

Embodiments of the electronic component according to the presentdisclosure are not limited to the electronic components 10 and 10 a to10 d, and the electronic component may be modified within the scope notdeparting from the gist of the present disclosure.

The configurations of the electronic components 10 and 10 a to 10 d maybe optionally combined with one another.

In the electronic component 10, the coil conductor layer 30 a and theparallel coil conductor layer 36 are electrically connected in parallelthrough the connecting conductors 70 a and 70 d, the lead-out conductorlayer 60, and the interlayer connecting conductor v1. As an alternative,the coil conductor layer 30 a and the parallel coil conductor layer 36may be electrically connected in parallel through only an interlayerconnecting conductor, or through a combination of the connectingconductors 70 a and 70 d and a connecting conductor layer without usingany interlayer connecting conductor. The above point is similarlyapplied to the electrical parallel connection with respect to the othercoil conductor layers and the parallel coil conductor layer.

In the electronic component 10 a, as illustrated in FIG. 8B, each of thecoil conductor layers 30 a, 32 a, 32 b, 34 a and 34 b has the thicknessd1, and each of the coil conductor layer 30 b and the parallel coilconductor layer 36 has the thickness d2. The thickness d1 is larger thanthe thickness d2. However, the thickness of each of the coil conductorlayers 30 a, 30 b, 32 a, 32 b, 34 a and 34 b and the thickness of theparallel coil conductor layer 36 are not limited to the above-describedrelation. For example, the thickness of each of the coil conductorlayers 30 a and 30 b and the thickness of the parallel coil conductorlayer 36 may be substantially equal to each other. In that case, thethickness of each of the coil conductor layers 30 a and 30 b and thethickness of the parallel coil conductor layer 36 are preferablydesigned, for example, such that a conductor volume of the primary coilL1, a conductor volume of the secondary coil L2, and a conductor volumeof the tertiary coil L3 are substantially equal to one another. Thus,the thickness of each of the coil conductor layers 30 a and 30 b and thethickness of the parallel coil conductor layer 36 are set to about ⅔ ofthe thickness of each of the coil conductor layers 32 a, 32 b, 34 a and34 b. In the above case, since conditions in laminating the coilconductor layers 30 a and 30 b and the parallel coil conductor layer 36are the same, it is possible to reduce stress concentration caused bythe difference in the layer thickness, to improve reliability, and torationalize the manufacturing steps.

While the electronic components 10 and 10 a to 10 d are fabricated byphotolithography in the above embodiments, they may be fabricated, forexample, by a lamination technique of laminating insulator layers onwhich the coil conductor layers are printed.

One example in which the intervals between two of the coil conductorlayers 30 a, 30 b, 32 a, 32 b, 34 a and 34 b and the parallel coilconductor layer 36, every two of those being adjacent to each other inthe up-down direction, are not even has been described above as anexample in which, like the electronic component 10 a of FIG. 8B, theinterval between the coil conductor layer 34 b and the parallel coilconductor layer 36 is larger than the intervals between two coilconductor layers among the coil conductor layers 30 a, 30 b, 32 a, 32 band 34 a, every two of those being adjacent to each other in the up-downdirection. In the electronic component 10 a, the intervals between twocoil conductor layers among the coil conductor layers 30 a, 30 b, 32 a,32 b and 34 a, every two of those being adjacent to each other in theup-down direction, are all substantially equal to one another. However,at least one or more of the intervals between two coil conductor layersamong the coil conductor layers 30 a, 30 b, 32 a, 32 b and 34 a, everytwo being adjacent to each other in the up-down direction, may bedifferent from the other interval(s), or the intervals between two coilconductor layers among the coil conductor layers 30 a, 30 b, 32 a, 32 band 34 a, every two of those being adjacent to each other in the up-downdirection, may be all different from one another. Even with theconfigurations described above, matching of the differential impedancecan be held in some cases depending on layouts of the signal lines 604,606 and 608 in the circuit board 600. In one concrete example of thoselayouts, the interval between the signal line 604 and the signal line606 is different from the interval between the signal line 606 and thesignal line 608.

While, in the electronic component 10 a, the parallel coil conductorlayer 36 is connected to the coil conductor layer 30 b in parallel, theparallel coil conductor layer 36 may be, as another example, connectedto the coil conductor layer 30 a in parallel.

As described above, the present disclosure is usefully applied toelectronic components. In particular, the present disclosure is superiorin a point that, in an electronic component including a common modefilter constituted by three coils, differential impedances between twoamong those coils can be adjusted.

While preferred embodiments of the disclosure have been described above,it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the disclosure. The scope of the disclosure, therefore, isto be determined solely by the following claims.

What is claimed is:
 1. An electronic component comprising: a multilayerbody constituted by insulator layers that are laminated in a laminatingdirection; a primary coil including one or more primary coil conductorlayers and at least one parallel coil conductor layer, each disposed onone of the insulator layers; a secondary coil including one or moresecondary coil conductor layers each disposed on one of the insulatorlayers; and a tertiary coil including one or more tertiary coilconductor layers each disposed on one of the insulator layers, whereinthe primary coil conductor layers, the secondary coil conductor layers,the tertiary coil conductor layers, and at least one parallel coilconductor layer are arrayed in the laminating direction such that everytwo coil conductor layers are adjacent to each other with an intervaltherebetween in the laminating direction, the primary coil, thesecondary coil, and tertiary coil constitute a common mode filter, andan interval between the at least one parallel coil conductor layer andthe tertiary coil layers is different from the respective otherintervals.
 2. The electronic component according to claim 1, wherein nis a natural number, the one or more primary coil conductor layersinclude n primary coil conductor layers and a parallel primary coilconductor layer disposed on one of the insulator layers, the one or moresecondary coil conductor layers include n secondary coil conductorlayers, the one or more tertiary coil conductor layers include ntertiary coil conductor layers, current paths of the primary coil, thesecondary coil, and the tertiary coil are substantially equal to oneanother in length, respective ones of the primary coil conductor layers,the secondary coil conductor layers, and the tertiary coil conductorlayers are arrayed in a mentioned order from one side toward the otherside in the laminating direction and constitute a coil conductor layergroup, n coil conductor layer groups are arrayed from the one sidetoward the other side in the laminating direction, the parallel primarycoil conductor layer is electrically connected to a predeterminedprimary coil conductor layer in parallel, has a substantially same shapeas the predetermined primary coil conductor layer in a plan view whichis a one viewed from the laminating direction, and is disposed on theother side in the laminating direction relative to a predeterminedtertiary coil conductor layer which is the tertiary coil conductor layerdisposed at a farthest position on the other side in the laminatingdirection, and an interval in the laminating direction between theparallel primary coil conductor layer and the predetermined tertiarycoil conductor layer is larger than respective intervals between two ofthe primary coil conductor layers, the secondary coil conductor layers,and the tertiary coil conductor layers.
 3. The electronic componentaccording to claim 2, wherein n is a natural number of two or more, atotal of a sectional area of the predetermined primary coil conductorlayer and a sectional area of the parallel primary coil conductor layeris substantially equal to a sectional area of each of the primary coilconductor layers other than the predetermined primary coil conductorlayer.
 4. The electronic component according to claim 2, wherein thesectional area of the predetermined primary coil conductor layer and thesectional area of the parallel primary coil conductor layer aresubstantially equal to each other.
 5. The electronic component accordingto claim 2, wherein the total of the sectional area of the predeterminedprimary coil conductor layer and the sectional area of the parallelprimary coil conductor layer is substantially equal to a sectional areaof each of the secondary coil conductor layers, and is substantiallyequal to a sectional area of each of the tertiary coil conductor layers.6. The electronic component according to claim 2, wherein a volume ofthe primary coil, a volume of the secondary coil, and a volume of thetertiary coil are substantially equal to one another.
 7. The electroniccomponent according to claim 2, wherein the respective intervals betweentwo of the primary coil conductor layers, the secondary coil conductorlayers, and the tertiary coil conductor layers are substantially even.8. The electronic component according to claim 2, wherein each of theprimary coil conductor layers has a substantially spiral shape in theplan view, and the electronic component further comprises: a first outerelectrode; and a first lead-out conductor layer not having asubstantially spiral shape in the plan view, wherein the primary coilconductor layers include an end primary coil conductor layer, and thefirst lead-out conductor layer relays connection between an inner endportion of the end primary coil conductor layer and the first outerelectrode, and is disposed between the parallel primary coil conductorlayer and the predetermined tertiary coil conductor layer.
 9. Theelectronic component according to claim 8, wherein each of the secondarycoil conductor layers and the tertiary coil conductor layers has asubstantially spiral shape in the plan view, and the electroniccomponent further comprising: a second outer electrode; a third outerelectrode; a second lead-out conductor layer not having a substantiallyspiral shape in the plan view; and a third lead-out conductor layer nothaving a substantially spiral shape in the plan view, wherein thesecondary coil conductor layers include an end secondary coil conductorlayer, the tertiary coil conductor layers include an end tertiary coilconductor layer, the second lead-out conductor layer relays connectionbetween an inner end portion of the end secondary coil conductor layerand the second outer electrode, and is disposed between the parallelprimary coil conductor layer and the predetermined tertiary coilconductor layer, the third lead-out conductor layer relays connectionbetween an inner end portion of the end tertiary coil conductor layerand the third outer electrode, and is disposed between the parallelprimary coil conductor layer and the predetermined tertiary coilconductor layer, and the first outer electrode, the second outerelectrode, and the third outer electrode are arrayed in a mentionedorder in a predetermined direction that is perpendicular to thelaminating direction.